This application is based on Patent Application No. 11-244007 filed in Japan, the content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a fixing roller and a fixing device using same for fixing an image of unfixed toner on a recording member.
2. Description of the Related Art
With the increasing awareness of environmental issues in recent years, studies were begun on the re-use of components and parts used in copiers and printers. Methods of re-use include methods for reducing parts to basic levels and reforming and finishing as has been generally done conventionally for paper and aluminum cans, and methods wherein only the depleted parts are reproduced.
The fixing roller for applying heat to fix an unfixed toner image on a recording member used in printers and copiers uses aluminum, iron or the as a base member over which is formed a surface coat layer formed of Teflon resin, silicon rubber or the like.
The service life of such a fixing roller is determined by the deterioration, wear, and damage to the material of the surface coat layer formed on the exterior surface of the base member, since there is little change of the base member part over time. However, problems arise when the base member part is directly re-used. Specifically, the boss of the fixing roller is subject to wear and damage through contact and rubbing against other parts, so as to require reproduction. This reproduction work requires time, labor, and cost.
Bushings made of heat-resistant resin are inserted between the boss at both ends of the base member and the bearings which received them so as to prevent heat damage caused by thermal transfer. Discrepancy of the dimension, position, and inclination of the boss and the heat-resistant resin bushing is the cause of abrasion of the boss and bushing. In general, it is extremely difficult to eliminate this discrepancy, and the bushing becomes worn. When the bushing becomes worn, one may consider replacing the bushing with a new bushing, however, heat-resistant resin is expensive. In addition, disposing of the heat-resistant resin bushing leads to the problem of environmental pollution.
On the other hand, it has been proposed to make the boss of the base member of heat-resistant resin and screw attach this boss to the end of the metal base member. Such an arrangement would allow the base member to be re-used by simply replacing the boss, and would not incur time and labor. It has been further proposed that the boss of the base member be formed of stainless steel having a high wear resistance. Such an arrangement would reduce the wear and damage to the boss and extend its service life.
Since the boss of the base member is formed of heat-resistant resin, however, the replacement of a boss formed of expensive heat-resistant resin as described above is influenced by cost even though it is advantageous to re-use the base member. Furthermore, disposing of the heat-resistant resin waste material leads to the disadvantage of environmental pollution. Even forming the boss of the base member using stainless steel does not prevent wear of the boss, and even slight wear of the boss requires reproduction of the base member, an operation also incurring cost. Mixing aluminum, iron, and stainless steel forms an alloy which is ultimately re-usable by melting, a process which is troublesome.
In view of the aforesaid information, the present invention relates to an improved fixing roller and fixing device using same.
The present invention provides an easily re-usable fixing roller and fixing device using this fixing roller, and this re-use does not require labor or cost.
These and other objects are attained by one aspect of the present invention which is a fixing roller which heat-fixes an unfixed toner image on a recording member transported between the fixing roller and another rotating member, wherein the fixing roller is provided with a base member, a surface coat layer provided on the surface of the base member and which comes into contact with the recording member during the fixing process, and a silica protective layer provided over the part of the surface not provided with the surface coat layer.
According to this construction, the fixing roller heat-fixes the toner image via the applied heat as the recording member bearing the unfixed toner image is transported between the fixing roller and the other rotating member. At this time, an excellent fixing result is attained by satisfying surface conditions wherein the surface coating of the fixing roller comes into contact with the recording member and the toner carried thereon, and a nip width necessary for the separation of the recording member and for heat fixing is formed by elastic deformation.
During the fixing process, the surface coat layer provided on the base member of the fixing roller deteriorates, becomes worn and damaged over time, until it eventually reaches the end of its serviceable life. However, the surface of the part of the base member not provided with the surface coat layer is provided with a silica protective layer which is extremely thin but protects by means of its high hardness, wear resistance and corrosion resistance. That is, wear and damage associated with changes in service life caused by contact with the bearing and other parts providing support for the rotational drive are prevented at the part of the base member not provided with the surface coat layer. In this way the service life of the base member is extended, and the base member can be directly re-used without labor or cost of a recycling operation by simply peeling off the surface coat layer when the end of its service life has been reached. A further advantage is that a mixture of different metals is not required in the base member.
When the silica protective layer is obtained by calcination of perhydropolysilazane, the layer may be formed by a low temperature operation, and can prevent deterioration of the surface and deformation of the base member even when the base member is made of conventional material such as aluminum or iron.
Even if the silica protective layer is provided on the surface of the bearing-supported part and other contact parts and oscillating parts formed of heat-resistant resin of the base member, a similar protection can be obtained when the heat-resistant resin is part of the base member.
According to another aspect of the present invention, the fixing roller heat-fixes an unfixed toner image on a recording member transported between the fixing roller and another rotating member, wherein the fixing roller is provided with a base member, a surface coat layer provided on the surface of the base member and which comes into contact with the recording member during the fixing process, and a silica protective layer provided over the part of the surface provided with the surface coat layer which oscillates with a thermo switch and the like.
According to this construction, the part of the surface coat layer which oscillates with a thermo switch or the like which detects temperature of the surface coat layer during use of the fixing roller is protected by the high hardness and wear resistance of the silica protective layer. In this way reduction of the service lifer of the surface coat layer through oscillation of other parts is prevented. In this case, when the silica protective layer is provided on the base member, it may be formed by calcination of perhydropolysilazane at low temperature to thermally protect the surface coat layer.